All right to use the term if the context requires it, but minorities is usually the better word (since it includes homosexuals, weirdos, communists, criminals and the like). Certainly, it should be used instead of black or Afro. Sometimes Negro Supremacist is good to refer to pro-minority interests. Avoid hyphenating (and, thereby, demeaning) the word American, such as with African-American, Mexican-American and the like.